1. Field of the Invention
The present invention pertains to torque verifying or measuring devices. More particularly, the present invention pertains to automated torque measuring devices. Even more particularly, the present invention concerns automated devices for verifying that an applied torque to a fastener is at a minimum value.
2. The Prior Art
The need for the measurement or verification of the torque which has been previously applied to nuts, bolts and other fastening devices is well known. This is especially true in the assembly of mass produced devices. As is well-known to the skilled artisan, if the torque applied to nut, bolt or other such rotatably mounted fastener is either inadequate or excessive, then serious consequences to any assembly employing such fasteners may be encountered. Thus, it is essential that the torque previously applied to a fastener be accurately measured and/or verified to assure that it is greater than a minimum value.
Heretofore, the prior art has proposed devices for measuring or checking the torque which has previously been applied to a fastener. Typically, such prior art devices include a motor, a torque transducer, a rotating spindle having a fastener engaging socket and a rotation sensor. In use, the motor and the spindle are used to apply a torque to the fastener to cause the fastener to start to rotate. The sensor detects or senses the commencement of rotation of the fastener and the torque transducer measures the applied torque thereat. As rotation of the fastener begins and is sensed, the motor is stopped. However, because of the inertia of the motor, the motor continues to rotate. This additional rotation is imparted to the spindle and to the fastener, causing an increase in applied torque to occur. This additional torque, called torque overshoot, causes, in some instances, excessive torque to be applied to the fastener; gives inaccurate applied torque checking, and, also, upsets the relationship between the components of the assembly with which the fastener is associated. The problems associated with any one of these consequences is readily apparent.
Thus, a major advance in the art would be provided by a torque verifying or checking device which minimizes torque overshoot and which, in operation, does not apply any further torque to the fastener being checked. As is subsequently detailed, the present invention achieves this.